A known image forming apparatus includes a process cartridge detachably attachable to a main body of the image forming apparatus by being guided by a guide provided in the main body. Specifically, the main body includes a casing having an opening that is open upward and a cover to open and close the opening. The guide is formed in the casing and extends diagonally from the opening to a rear side of the casing.
In the image forming apparatus, the cover includes a pressing portion configured to press the process cartridge being attached toward an attachment position when the cover closes the opening. The pressing portion is configured to contact a horizontal surface of the process cartridge and press the horizontal surface vertically.